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Proposition 1, p. 11 — cross-licensing weakly raises supplier profit ex post

Proved
CrossLicensing.ExPost.proposition_1

by mikedeng1 · Oct 16, 2026 · Mathlib 0df444a (Lean v4.33.1)

cross-licensingnash-equilibriump2o-batch-pfp2ap2o-gran-per-chapterp2o-plan-paperp2o-v1supplier-profit

Fix innovation levels 0≤T1≤T20\le T_1\le T_20≤T1​≤T2​, effectiveness 0≤β≤10\le\beta\le10≤β≤1, and a wholesale price r≥0r\ge0r≥0. The manufacturers' quantity game has a Nash equilibrium both with cross-licensing at effectiveness β\betaβ and without it at β=0\beta=0β=0. For every equilibrium qclq^{\mathrm{cl}}qcl of the former game and every equilibrium qnq^{\mathrm n}qn of the latter,

r(q1n+q2n)≤r(q1cl+q2cl).r\bigl(q^{\mathrm n}_1+q^{\mathrm n}_2\bigr)\le r\bigl(q^{\mathrm{cl}}_1+q^{\mathrm{cl}}_2\bigr).r(q1n​+q2n​)≤r(q1cl​+q2cl​).

This is the supplier's ex-post profit comparison at the same innovation levels and the same wholesale price. Formalization Note The weak inequality permits equality, in particular at β=0\beta=0β=0. The paper's second sentence interprets this comparison as the final contract choice; it does not specify a separate contract-stage game. Nonnegative rrr is made explicit because the claim fails at a negative wholesale price.

Preamble
import Mathlib
import Definitions.Def_CrossLicensing_ExPost_Model
Formal statement
namespace CrossLicensing.ExPost

/-- Proposition 1: cross-licensing weakly increases supplier profit at the same
innovation levels and wholesale price, for every pair of quantity equilibria. -/
theorem proposition_1 (β T₁ T₂ r : ℝ) (h : Standing β T₁ T₂ r) :
    (∃ q, IsQuantityNE β T₁ T₂ r q) ∧
    (∃ q, IsQuantityNE 0 T₁ T₂ r q) ∧
    (∀ qcl qn, IsQuantityNE β T₁ T₂ r qcl → IsQuantityNE 0 T₁ T₂ r qn →
      supplierProfit r qn ≤ supplierProfit r qcl) := by sorry

end CrossLicensing.ExPost
Source
Wang, Huang, Lee, Cross-licensing in a Supply Chain with Asymmetric Manufacturers, SSRN 3053682 (version of 2023-04-27), p. 11, Proposition 1; proof p. A.1 (PDF 33)
Human review
  • Endorsed by Shuze Chen · Oct 16, 2026

    Confirmed by the moderator at approval.

  • Endorsed by mikedeng1 · Oct 16, 2026

    Confirmed by the mission captain (proposal self-audit).

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